cell division by mitosis

• Why do multicellular eukaryotic organisms require a continuous supply of new cells?


  For growth, development, and repair
• What is the process through which new cells are generated called?

  The cell cycle
• What happens during the first step of the cell cycle?


  The cell grows in size and increases the number of subcellular structures
• What occurs during DNA replication in the cell cycle?


  The DNA is duplicated for the two new cells
• How does DNA appear when a cell is not dividing?


  It is spread out in long strings
• What happens to DNA when a cell prepares for division?


  It condenses into chromosomes
• What do chromosomes contain?


  A large number of genes
• How many copies of each chromosome do eukaryotic cells have?


  Two copies, forming a pair
• How many pairs of chromosomes do humans have?


  23 pairs
• Why can't animals of different species reproduce fertile offspring?

  Because they have different numbers of chromosomes
• What shape do duplicated chromosomes take?


  An X shape
• What does each half of the X-shaped chromosome represent?


  A duplicate of the left half
• What happens to the chromosomes during cell division?


  They line up along the center of the cell
• What attaches to the chromosomes during cell division?


  Fibers from either side of the cell
• What is the term for the two sides of the cell during division?

  Poles
• What happens to the chromosomes as they are pulled to opposite sides of the cell?


  They break in half into two separate arms
• What is the final stage of the cell cycle called?

  Cytokinesis
• What occurs during cytokinesis?


  The cell membrane and cytoplasm pull apart, forming two daughter cells
• What is true about the resulting daughter cells after division?


  They have the same DNA and are identical to each other and the parent cell
• What can the resulting daughter cells contribute to after division?


  Growth, development, or repair
• What are the stages of the cell cycle?


  1. Growth
  2. DNA replication
  3. Mitosis (division or cytokinesis)
• What is the significance of chromosomes in cell division?


  • Chromosomes condense to ensure accurate DNA distribution
  • Each chromosome contains genes that determine characteristics
  • Eukaryotic cells have pairs of chromosomes from both parents
• The nucleus of a cell contains chromosomes made of DNA molecules. Each chromosome carries a large number of genes.
• In body cells the chromosomes are normally found in pairs.